1. Field of the Invention
The present invention relates to image forming apparatuses, such as copying machines and laser printers, that adopt an intermediate transfer system of an electrophotographic system or an electrostatic recording system for transferring a toner image formed on an image bearing member onto an intermediate transfer member and thereafter transferring the toner image onto a transfer material.
2. Description of the Related Art
In an image forming apparatus, part of toner may fail to be transferred from an intermediate transfer member to a transfer material, and this residual toner needs to be cleaned from the intermediate transfer member for the next printing. A proposed method for cleaning the residual toner uses a charge member for charging the residual toner and applies a voltage to the charge member to charge the residual toner to a predetermined polarity. In this method, a primary transfer member then moves the residual toner from the intermediate transfer member to a photosensitive drum.
Japanese Patent Application Laid-Open No. H10-49023 discloses that a roller with electrical conductivity is used as a charge member and provided with a release layer on a front layer thereof by coating or the like, thus suppressing adhesion of residual toner to the conductive roller.
However, in the configuration in Japanese Patent Application Laid-Open No. H10-49023, when a voltage is applied to the conductive roller, a discharge current may be locally generated to break part of the release layer of the conductive roller. Then, an excessive current may flow through the broken part. As a result, the excessive current may flow from the charge member into the intermediate transfer member. Furthermore, if the conductive roller includes the release layer, the conductive roller charges the residual toner in very small spaces located upstream and downstream of a charging nip formed by the conductive roller and intermediate transfer member contacted with each other. Thus, if the amount of the residual toner is large, the residual toner may fail to be sufficiently charged.